Connecting plug for a current supply rail arrangement intended particularly for lighting purposes and small-sized electrical motors

ABSTRACT

A connecting plug for a current supply rail, provided with contact fingers displaceable by means of manually turnable eccentrics from an inner inoperative position to an outer contact-making position. The plug is provided with locking means in engagement with the eccentrics for preventing turning of the eccentrics in an incorrect contact position of the plug in the current supply rail.

United States Patent Valtonen CONNECTING PLUG FOR A CURRENT SUPPLY RAILARRANGEMENT KNTENIDED PARTHCULARLY FOR LTGHTTNG PURPOSES AND SMALL-SlZlED ELECTRICAL MOTORS inventor: Rainer Ilkka Tapio Valtonen,Suomenoja,

Finland Assignee: 0y Nokia All, Helsinki, Finland Filed: Oct. 24, 1969Appl No.: 869,267

Foreign Application Priority Data Oct. 24, 1968 Finland 3026/68 US. Cl...339/75 M, 339/91 R int. Cl i ..H01rl3/54 Field of Search ..339/2124,75,

[ 51 Feb. 29, 1972 Primary ExaminerJoseph H. McGlynn Att0rneyWaters,Roditi, Schwartz & Nissen [57] ABSTRACT A connecting plug for a currentsupply rail, provided with contact fingers displaceable by means ofmanually turnable eccentrics from an inner inoperative position to anouter contact-making position. The plug is provided with locking meansin engagement with the eccentrics for preventing turning of theeccentrics in an incorrect contact position of the plug in the currentsupply rail.

4 Claims, 9 Drawing Figures PATENTEBFEBZSIBYE 3,646,501

sum 2 [IF 2 FIG. 8

CONNECTING PLUG FOR A CURRENT SUPPLY RAIL ARRANGEMENT INTENDEDPARTICULARLY FOR LIGHTING PURPOSES AND SMALL-SIZED ELECTRICAL MOTORS Thepresent invention relates to a connecting plug for a current supply railarrangement equipped with current conductors and a protective groundinglead, the connecting plug consisting of a casinglike body, separateflexible contact fingers attached to the body and a rotating eccentricfor each contact fingerjournaled in the body, which eccentric on beingrotated displaces the respective contact finger between a positionretracted into the casing and a position protruding from the casing andcontacting the current conductors in the current supply rail.

An earlier connecting plug of this type is known, i.e., from the FinnishPat. No. 40,644, the Austrian Pat. No. 278,l3l and the GermanGerbrauchsmuster No. 1,989,491. As connecting plugs of this type areused in connection with threephase current supply rails it is possiblein practice that the connecting plug due to careless coupling to thesupply rail is not pushed right to the bottom of the rail and that theeccentrics are thereupon rotated in the usual way in order to make thecontact fingers contact the current conductors in the supply rail. Theresult is that only part of the contact fingers get into touch with thecurrent conductors without the grounding fingers of the connecting plugbeing in contact with the grounding lead of the supply rail. The rest ofthe contact fingers are on the other hand quite bare outside the supplyfingers rail and may consequently be touched by hand. The bare contactfingers become current-carrying through the consumer apparatus, when thelatter is switched on. Considering that protective grounding has notbeen effected either, the defective coupling of the connecting plug maycause serious accidents.

The object of the present invention is to produce a more reliableconnecting plug, by the use of which the foresaid risks of accidentswill be avoided.

This is achieved by using a connecting plug according to the presentinvention, characterized in that the connecting plug is provided with alocking device, which is arranged so that it by the action of thecurrent supply rail is displaced away from a position preventing therotating of the eccentrics when the connection plug is pushed to thebottom of the supply rail.

The arrangement according to the present invention makes it impossibleto turn out the contact fingers before the connecting plug is pushedinto the supply rail right down to the bottom of it, because the lockingdevice releases the eccentrics to be rotated only after the connectingplug is altogether pushed into the current supply rail. This releasingand locking operation takes place automatically when pushing in orpulling out the connecting plug and does not consequently require anyextra manipulations. The construction of the locking device is verysimple and known connecting plugs may by means of simple constructionalmodifications be made reliably usable.

The invention will be described in the following more in detail withreference to the accompanying drawings, wherein FIG. I shows a side viewof a first embodiment of the connecting plug,

FIG. 2 shows in cross section a known current supply rail of theconnecting plug,

FIG. 3 shows a side view of the connecting plug, in partial section,

FIG. 4 shows a section along line IVIV in FIG. 3,

FIG. 5 shows a section along line V-V in FIG. 3,

FIG. 6 shows a section along line VI-VI in FIG. 3,

FIG. 7 shows a section along line VIIVII in FIG. 9 of a secondembodiment of the connecting plug according to the invention,

FIG. 8 shows a cross section of a current supply rail for the connectingplug according to FIG. 7,

FIG. 9 shows partly a section a side view of the connecting plug.

The three-phase supply rail arrangement shown in FIG. 2, comprises ametal rail 1 serving as protective grounding lead and supportingstructure, to which insulating and fastening strips 2 are attached, inwhich are embedded current conductors 3, 4, 5 and 6 (threephase-conductors and one zero-conductor).

The connecting plug 7 shown in FIG. 1 comprises a casing 15 covering abody 16, to which contact fingers 8, 9, l0 and 11 are flexibly attached,which are intended to contact the current conductors 3, 4, 5 and 6 inthe supply rail, whereas contact fingers l2 and 13 are intended tocontact the metal rail 1 in order to achieve protective grounding. Aturning spindle 17 is journaled in the body and formed with a number ofeccentrics 18, one eccentric for each contact arm, and in addition atone end provided with a knob 14 for rotating the spindle. By rotatingthe spindle 17 the contact fingers may by means of the eccentrics bedisplaced between an outside position, where the contact fingers areprotruding from the casing, and an inside position, where the contactfingers are retracted into the casing. The connecting plug is intendedto be pushed into the current supply rail according to FIG. 2 with thecontact fingers being in their inside position, whereupon the contactfingers by the turning of the knob are brought into their outsideposition, where contact fingers 8-11 make contact with the currentconductors 3-6 whereas contact fingers 12-13 make contact with the metalrail 1.

The construction and function of the connecting plug so far describedare previously known.

One end of the turning spindle is journaled in the body 16 in such anotch 16a, FIG. 6, that the spindle may be turned by means of the knob14, i.e., between said position where the contact fingers are keptinside the casing and said position where the eccentrics are pressingthe contact fingers out of the casing, as described above.

The connecting plug is in order to be in the right contacting positionexpected to be completely pushed into the supply rail. However, it isevident that the connecting plug can also be pushed only partly into thecurrent supply rail, and in order to prevent the contact fingers frombeing moved in such a case into their outside position by turning theknob 14 a locking device is arranged.

In the embodiment, according to FIGS. 1-6 there is formed on the turningspindle at the middle eccentric 18 a protruding locking cam 19, FIG. 3and 4, and to the body 16 there is attached a resilient locking clasp20, which is engaged with the cam 19 so as to prevent the spindle 17from being rotated. Between the locking clasp 20 and the contact finger12 there is slidably positioned a slide 21, FIG. 3 and 4, the upper endof which forms an operating element 21a protruding out of the edgesurface 15a of the casing, and which is provided with an oblique guidingsurface 21.

As the connecting plug is pushed into the supply rail right to thebottom, the operating element 21a strikes against the opening edge la ofthe supply rail, whereby the slide is pushed inside the casing. Theoblique guiding surface 21b of the slide forces then the locking clasp20 away from the eccentric I8, causing the locking cam 19 to getreleased from the locking clasp 20, whereby the turning spindle 17 isfree to be turned by means of the knob 14. As the connecting plug isbeing pulled out of the supply rail, the slide is on account of theoblique guiding surface 21b and the spring action of the locking clasp20 forced back to its starting position, whereupon the locking claspagain gets engaged with locking cam 19. It is noticed, that the rotatingof the eccentrics is blocked until the connecting plug is pushed in toreach the bottom of the current supply rail.

In the embodiment according to FIGS. 7-9 a pivoting double-armed lever23 is mounted on a pivot shaft 22 in the body, one arm of the leverforming an operating element 24 protruding from the top surface 15b ofthe casing while the second arm is forming an U-shaped locking element25. The turning spindle 17 is formed with an end part 26 having arectangular cross section, which fits into the U-shaped locking element25 FIG. 9.

As the connecting plug is pushed into the supply rail 1 right to thebottom thereof, the operating element 24 of the lever strikes againstthe bottom surface lb of the supply rail, whereby the operating elementis pushed into the casing and the lever is turned anticlockwise (FIG. 9)round the pivot shaft so that the locking element 25 is pushed away fromits engagement with the end part 26 of the turning spindle and thespindle is free to be turned by means of the knob 14. As the connectingplug is pulled out from the supply rail the lever is returned to itslocking position by means of a spring 27, whereupon locking positionelement again gets engaged with the end part 26 of the spindle. It isobserved that the rotating of the eccentrics is locked until theconnecting plug is pushed in right to the bottom of the supply rail.

In the embodiment according to FIGS. 7-9 the lever 23 is made ofelectric conductor material and connected by means of a flexible cable28 with a grounding contact screw 29. The current supply rail isequipped with a special protective grounding lead 30, which theoperating element 24 of the lever 23 contacts, when the plug is pushedinto the rail. In this connection, the function of the contact fingers12-13 is only to serve as holding means for the connecting plug in thesupply rail.

The operating element of the locking device is in both embodimentspreferably arranged to protrude nearby the center of the connecting plug(FIGS. 3 and 9) in order to prevent that the locking action of thelocking device is affected by an oblique insertion of the plug into thesupply rail.

The drawings and descriptions referring to them are only intended toexemplify the idea of the invention. As to details, the connecting plugmay vary considerably within the scope of the invention.

1 claim:

1. A connecting plug for a current supply rail arrangement provided withcurrent conductors and a protective grounding lead, particularly forlighting purposes and small electric motors, said plug comprising; acasinglike body, contact fingers being separately flexibly fastened inthe body; an eccentric for each said contact finger rotatably joumaledin the body, each said eccentric upon being rotated displacing acorresponding contact finger between a position retracted within acasing and a position protruding therefrom for contact with the currentconductors in the current supply rail; and a locking device adapted tobe displaced by the action of the supply rail away from a positionlocking the rotation of the eccentrics as the plug is pushed to thebottom of the supply rail, said locking device comprising a locking camformed on a turning spindle connecting said eccentrics, a locking claspattached to said body and engaged with the locking cam; and a slidepositioned in said body, said slide having one of end forming anoperative element having a guiding means, said slide being displaceablebetween a locking position in which said operative element protrudesfrom said casing, and a releasing position in which said operativeelement is pushed into the casing and said guiding means displaces thelocking clasp from its engagement with the locking cam.

2. A connecting plug as claimed in claim 1, wherein said operativeelement of the slide is adapted to protrude from the center portion ofsaid casing, said portion being adapted to be positioned against theedge of an opening in the current supply rail.

3. A connecting plug for a current supply rail arrangement provided withcurrent conductors and a protective grounding lead, particularly forlighting purposes and small electric motors, said plug comprising; acasinglike body; contact fingers being separately flexibly fastened inthe body; an eccentric for each said contact finger rotatably joumaledin the body, each said eccentric upon being rotated displacing acorresponding contact finger between a position retracted within acasing and a position protruding therefrom for contact with the currentconductors in the current supply rail; and a locking device adapted tobe displaced by the action of the supply rail away from a positionlocking the rotation of the eccentrics as the plug is pushed to thebottom of the supply rail, said locking device comprising a lockingmeans formed on a turning spindle connecting the eccentrics, and apivoting lever joumaled in said body, said lever having one arm formingan operative element and another arm forming a locking element, saidlever being pivotable between a locking position in which said operativeelement protrudes from said casing so as to engage the locking elementwith the locking element with the locking means on said spindle and areleasing position in which the operative element is pushed into thecasing and the locking element is disengaged from said locking means.

8. A connecting plug according to claim 3, wherein said operativeelement of the lever is adapted to protrude from the center portion ofsaid casing, said portion being adapted to be positioned against thebottom of said current supply rail.

1. A connecting plug for a current supply rail arrangement provided withcurrent conductors and a protective grounding lead, particularly forlighting purposes and small electric motors, said plug comprising; acasinglike body, contact fingers being separately flexibly fastened inthe body; an eccentric for each said contact finger rotatably journaledin the body, each said eccentric upon being rotated displacing acorresponding contact finger between a position retracted within acasing and a position protruding therefrom for contact with the currentconductors in the current supply rail; and a locking device adapted tobe displaced by the action of the supply rail away from a positionlocking the rotation of the eccentrics as the plug is pushed to thebottom of the supply rail, said locking device comprising a locking camformed on a turning spindle connecting said eccentrics, a locking claspattached to said body and engaged with the locking cam; and a slidepositioned in said body, said slide having one of end forming anoperative element having a guiding means, said slide being displaceablebetween a locking position in which said operative element protrudesfrom said casing, and a releasing position in which said operativeelement is pushed into the casing and said guiding means displaces thelocking clasp from its engagement with the locking cam.
 2. A connectingplug as claimed in claim 1, wherein said operative element of the slideis adapted to protrude from the center portion of said casing, saidportion being adapted to be positioned against the edge of an opening inthe current supply rail.
 3. A connecting plug for a current supply railarrangement provided with current conductors and a protective groundinglead, particularly for lighting purposes and small electric motors, saidplug comprising; a casinglike body; contact fingers being separatelyflexibly fastened in the body; an eccentric for each said contact fingerrotatably journaled in the body, each said eccentric upon being rotateddisplacing a corresponding contact finger between a position retractedwithin a casing and a position protruding therefrom for contact with thecurrent conductors in the current supply rail; and a locking deviceadapted to be displaced by the action of the supply rail away from aposition locking the rotation of the eccentrics as the plug is pushed tothe bottom of the supply rail, said locking device comprising a lockingmeans formed on a turning spindle connecting the eccentrics, and apivoting lever journaled in said body, said lever having one arm formingan operative element and another arm forming a locking element, saidlever being pivotable between a locking position in which said operativeelement protrudes from said casing so as to engage the locking elementwith the locking element with the locking means on said spindle and areleasing position in which the operative element is pushed into thecasing and the locking element is disengaged from said locking means. 4.A connecting plug according to claim 3, wherein said operative elementof the lever is adapted to protrude from the center portion of saidcasing, said portion being adapted to be positioned against the bottomof said current supply rail.